Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$243.77	7.576%	$262.238	$262.24	$262.25	$262.20
Purchase #2	$13.41	3.390%	$13.8646	$13.86	$13.85	$13.90
Purchase #3	$248.28	13.389%	$281.5222	$281.52	$281.50	$281.50
Purchase #4	$221.48	7.650%	$238.4232	$238.42	$238.40	$238.40
Purchase #5	$107.72	8.570%	$116.9516	$116.95	$116.95	$117.00
Purchase #6	$239.75	12.801%	$270.4404	$270.44	$270.45	$270.40
Purchase #7	$67.28	5.309%	$70.8519	$70.85	$70.85	$70.90
7 purchase totals =	$1,141.69		$1,254.2919	$1,254.28	$1,254.25	$1,254.30